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U.S. DEPARTMENT pF AGRICULTURE, 
BUREAU OF HJT0M0L9GY CIRCULAR Ko. 148. 

L O. I l< >W AKI >. I ntomoWM «ikI ( h.rf ol Burcu. 



TWO DESTRUCTIVE TEXAS ANTS. 



\V. I). HUNTER, 

//i Charge of Southern Field Crop J 



. OFFKE : 1*12 




BUREAU OF C\ TO UOLOGY. 

L. O. Howard, Entomologist and <'hi<f of Bureau. 

('. L. Mablatt, Entomologist and Acting Chief in Absence of chief. 

R. S. Clifton, Executive Assistant. 

W. F. Tastet, Chief Clerk. 

F. II. Chittenden, in charge of truck wop and stored product insect investigations. 

A. I>. Hopkins, in charge of forest insert investigations. 

VV. I>. Hunter, in charge of southern field crop insect investigations. 

F. M. Websti b, /'// charge of cereal and forage insect investigations. 

A. I,. Qttaintance, tn charge of deciduous fruit insect investigations. 

E. F. Phillips, in charge of bee culture. 

D. M. Kot.i ss, in charge <>f previ nting spread of moths, field worfo, 
Rolla P. Cubbie, in charge of (tlitoriu! work. 

Mabel Colcobd, in charge of library. 

Southern Field Crop [nsect Investigations. 
W. I >. Hunter, in charge. 

V. V. Bishopp, A. II. Jennings, II. 1'. Wood, \V. V. King, engaged in tick life- 

h istory in vest i<)<i I ions. 
W. D. Pierce, G. I). Smith, J. 1). Mitchell, Harry Pinkus, B. K. Coad, It. W. 

Mobeland, engaged in cotton-boll weevil investigations. 
A. C. Morgan. G. A. Rtjnneb, S. E. Crumb. I). ('. Pabman, engaged m totiacco 

insect investigations. 
T. E. Holloway, E. R. Barber, engaged in sugar can< insect investigations 

E. A. McGregor, W. A. Thomas, engaged in red spider nn<l other cotton insect 
investigations. 

J. L. Webb, engaged in ri<-< insect investigations. 

R. A. Cooley, D. L. Van Dink, A. F. Conbadi, C. C Kbumbhaab, collaborators. 
ii 



Circular No. 148. b ned Iprfl H 1912 

United States Department of Agriculture, 

BUREAU OK ENTOMOLOGY, 
L O. HOWARD, Entomologist and Chief of Hurc.iu. 



TWO DESTRUCTIVE TEXAS ANTS. 

Bj W. I> Hi mi it 
In (Itiinjt nf Southern Field-Crop Insiii Investigation*. 

THE CUTTING OR PARASOL ANT. 
i l tin texana Buckley. » 

The so-called cutting or parasol ant (Atta fa xana Buckle} | is well 
known to residents i>t" the region in which it occurs. The colonies 
are located in sandy soil, generally in the timber, and consist of kyvi 
mounds of considerable extent covered with numerous craters about 
1^ Inches in diameter. The ants have the habit <>f cutting the leaves 
from a great variety of plant > and of carrying them to their nests. 
In many case- the attack i- concentrated on one tree, which may be 
entirely defoliated in a single night. The species is of a reddish- 
brown color. The colonies contain individuals showing great dif- 
ferences in size. as will be explained later. 

DISTRIBUTION. 

The range of this species is rather restricted. It is known only 
from a limited area in south-central Texas, This area extends from 
the Brazos River as far north as Waco to the Gulf, westward as Ear 

as San Antonio, and southward to the vicinity of Alice. The ant is 
most common in the valley- of the Colorado. Guadalupe, Comal, and 
San Antonio Rivers. In these situations it i- evidently increasing 
in numbers from year to year. In many cases the nests occupy the 
land practically continuously for many mile- up and down the valley-. 

II \1MT-. 

The nests consist of underground chambers with several openings 
or craters. The surplus openings seem to he provided for the pur- 
pose <»f ventilating the underground passages. The nest- are located 

28482*— Cir. US- 12 



Z TWO DESTRUCTIVE ANTS. 

generally in sandy soil. The more compact soils seem to be un- 
favorable for their construction. A very common location for a 

colony is a sandy promontory, well lighted by the sun, in the bend 
of a river. 

The large irregular mounds arc due to the leveling by the wind 
and rains of the circular ridges of sand, brought from beneath 
the surface, which surround the openings. Consequently, each of 
the mounds is an indication of the activity of the ants for many years. 
Beneath these mounds are numerous chambers connected by narrow 
passages, and there may he direct connection by these channels over 
an area of several hundred square feet. 

The habits of this insect have attracted great attention from scien- 
tists and others. The ants cut the leaves from trees and carry 
them to the nests. Each leaf is finely divided and made into small 
pellets. In this work the mandibles and legs of the ants are utilized. 
The small masses are placed upon the so-called fungus garden, where 
they furnish a growing medium for the growth of a fungus which 
furnishes the colony with food. As the supply of fungus is con- 
sumed the ants add to the old mass, so that eventually the nests are 
found to contain large spongy formations on the outer portion of 
which the slender threads of the fungus are growing. Evidently 
the ants exercise great care in preventing the contamination of the 
fungus garden by any but the sole species of fungus that is utilized. 

The ant is active throughout the greater part of the year. In 
fact, it becomes quiet for only a very short time when the winter 
cold is most severe. It is disinclined to work during very hot 
weather. During the cooler months its activity extends through- 
out the day, but during the summer it is confined to the night. The 
distance over which foraging expeditions take place may be 200 
yards or even more. Practically all species of plants seem to be 
suitable for food, although it is noticeable that only one species is 
attacked at a time. Dr. W. M. "Wheeler, who has made very careful 
studies of these ants, has noted that the same colony may feed upon 
a wide variety of plants at different times, but he never observed 
the individuals of a colony collecting different varieties at the same 
time. 1 Among cultivated crops, cotton, corn, fruit trees, sorghum, 
and many others are attacked. Among wild plants, forest trees are 
favored, and frequently the Spanish moss is used. The various 
species of oaks seem to be more or less immune, either on account 
of the texture of the leaves or the tannic acid they contain. This 
immunity is by no means absolute, however, as Dr. Wheeler and Mr. 
J. D. Mitchell have observed the ant- making use of such rough 
leaves as those of the live oak. 



i Wheeler, W. M. The Fungus-Growing Ants of North America. Bui. Amer. Mua, Nat. 
Hist., vol. 23, Article XXXI. pp. 7J!l-742. 



PWO DESTRUCTIVE AHTB. 8 

The colonies of this ant are formed bj the ili^lit of the females to 
some point imi far distant from the nest. The queen alights, digs 
beneath the surface, deposits a small quantity of the fungus from 
the original nest, and on it deposits a number of egg 

i ORMS. 

This ;mt occurs in five forms, namely, soldiers, large workers 
(media), small workers (minima), males, and females. The soldiers 
are from 1" (<> 12 mm. in length, with enormously developed heads. 
The large workers, or media, resemble the soldiers, although 1 1 • » - 
head is somewhat smaller, and the length of the body is between 
■\ ;iii(l 9 nun. The small worker forms, called minima, are from t.5 
to 2.5 nun. in length. The head is >till -mailer than in the media. 
Each of these three forms has a special function in the nest. The 
soldiers are concerned primarily with the protection of the nest. 
They do not sting, l>nt bite with their mandibles, which arc strong 
enough to draw blood. The large worker- and small workers are 
busied principally with the gathering of lease- for the fungus garden 
ami the preparation of the material on which the fungus grows. 
The remaining form- are the male- and female-. These are much 
larger than the other form-. The female is about I s nun. in length. 
The color i- dark brown, although the legs are somewhat reddish. 
The body i- covered with dense tawny hair. The wings, which are 
shed soon after the flight of the queen, are reddish In-own. especially 

along the anterior borders. The male- are from 13 to 1 I nun. long 
with a head of -mall -i/e which contrasts greatlj with that of the 
worker form-. The body is densely covered with long yellowish 

hair-, a- i- the case with the female-. 

l:l PR] S8ION. 

The fact that tlii- ant doe- not continue to attack one specie- of 

plant continuously, but changes from one to another at frequent 
interval-, causes it to he of less importance in the destruction of 
vegetation than it would he otherwise. Nevertheless, the damage 
to growing crop- i- frequently heavy, ami complaint- have become 
more numerous in recent year- on account of the greater abundance 
of the ant.-. In many place- considerable area- of land are not 
planted to crop- on account of the danger of attack. In all such 
situations it i- necessary to resort to repressive mean-. 

The best method of control i- undoubtedly by mean- of potassium 
eyanid.' Mr. .1. 1). Mitchell ha- conducted the experiments upon 

'Tin' nae of potassium cyan Id In water notation against n i-r followed by 

Messrs. i; S Woglum and Win Wood (See Journal of Economic (Entomology, v. a. 1, 

■ i'"'- \i,- ii i) Marsh b d It. (Se< Bui 04 Pi i v i s 

Depl Agr . Boj Knt . pp. Tt 78, L910 I 



4 TWO DESTRUCTIVE ANTS. 

which this conclusion is based. He used 98 per' cent potassium 
cyanid at the rate of 1 ounce to 1 quart of water. After careful 
mixing this liquid was poured into each of the openings in several 
nests, a quart to each opening. In every case it was found that the 
destruction of the colony followed after one or two applications. 
The cost of this method is small, but of course will assume consider- 
able proportions in areas where the ants are very numerous. Even 
under such conditions it will undoubtedly well pay for the expense 
and is advised above all methods that can be followed. 

The use of carbon bisulphid is not practical on account of the very 
extensive excavations the ants make in the sand. Some may be killed, 
but effective work can not be done unless the insecticide is forced into 
the earth by pressure, and this requires special apparatus. Moreover, 
the expense would be much greater than in the case of the cyanid 
method just described. 

Some years ago certain persons in southern Texas followed the 
destruction of this ant as a regular business. They used sulphur and 
a special apparatus for forcing the fumes into the nests. The ma- 
chine consisted of an oven in which the sulphur was burned. The 
fumes were passed through a pipe by forced draft, and the end of 
this pipe was inserted into the ground in the middle of the colony. 
Before the oven was started all of the openings of the nest were care- 
fully closed. It is said that remarkable success accompanied this 
method. It may be found to be advisable to use this method for 
large areas of the infested lands or where several planters can 
cooperate. 

Mr. C. L. Marlatt has described a method of destruction of ants 
which is in use in Cuba : 

It consists in digging a hole C, feet deep by 3 or 4 feet wide in the midst of 
the colony. This hole is filled with dry brush and a roaring fire started. Into 
this is then poured a bucketful of powdered sulphur. The opening is closed 
with a large iron plate. Through a hole in the center of this plate air is 
forced down into the burning mass with a large bellows. 1 

THE AGRICULTURAL OR HILLOCK ANT. 
(Pogonomyrmex barbatus molefaciens Buckley.) 

The nests of the agricultural or hillock ant (Po</<momyrm£X har- 
batus molefaciens Buckley) are conspicuous in the territory in which 
they occur on account of the fact that the ants do not allow an} 7 
vegetation to grow in a circular area about them. The mounds are 
l."» inches or more in diameter and are frequently covered with parti- 
cles of earth or sand from beneath the surface which contrast strongly 
with the surrounding soil. The bare areas around the mound may 
be 10 feet or more in diameter. 

•See W. M Wheeler: Ants, their structure, etc., p. r>77. 1010. 



PWO DESTRUCTIVE ANTS. D 

in- 1 kii'.i noN. 

The agricultural anl occurs from the Brazos River westward. 
West of San Antonio it is replaced l>\ closely allied forms. Farther 
north, in Kansas and Nebraska, a distinct species i/'. occidentalis 
Cress.) occurs. The agricultural an( is conspicuously a residenl of 
open places and does not occur in wooded localil 

it \r.i i-. 

This iint -warm- early in the season, generally after a rain. At 
such times tin" males and females come out of the ne-t in great num- 
bers, covering the ground for many feet Mating takes place at tlii- 
time, after which the females fly away. When they alight their 
wings are cast and they begin to dig a cell for ;i new colony. The 
males after mating arc driven away by the worker- or killed if they 
persist in returning to the nest. At the time of this swarming multi- 
tudes of the ants arc destroyed by birds and horned Lizards 

Many year- ago it was announced that the agricultural anl actu- 
ally plants certain grasses in order to obtain quantities <>t' Beed to use 
in provisioning the nests. In fact, it was on this supposition thai 
one of the common names which have come into use was given it. 
Upon careful investigation, however, it was found thai the ant does 
not plant seed intentionally, although it undoubtedly doe- so acci- 
dentally. The fact- were broughl out by Prof. \V. M. Wheeler. The 
seeds of several species of <_rra-s and common weed- are taken into 

the nest-. When the moisture is too great in the nest -on f these 

-ted- sproul and thu- hecoiue unsuitable for fond. Under such cir- 
cumstances the ant- carry out the sprouted seeds and deposit them in 
the immediate vicinity of the ne-t where many take root and grow. 
Of course, this can not be considered intentional planting of the 
seed-, because the ants deal with the sprouted grain exactly as they 
would with any substance that was unsuitable in their ne-t-: that is, 
they .-imply carry it out and throw it away. 

n \m \cr. 

The economic importance of the agricultural ant i- due t<> the fad 
that it will not allow vegetation to grow in the immediate vicinity 
of its nest and to it- powerful sting which it uses on the slightest 
provocation. If the colonic- happen to be in field- such a- alfalfa, 
corn, or cotton, the area of loss may amount to considerable, and the 
same i- true to a certain degree of pasture and range land-. More 
over, in fields which are mowed the mound- interfere with the work- 
iiiiT of the machine, and the anl- are likely to attack the horses. 
There i- some degree of compensation for the loss of the land cleared 
by the ants. It will be noted that in a circle ju-l outside of the area 



6 TWO DESTRUCTIVE ANTS. 

that is cleared the plants grow with great luxuriance. Frequently 
these plants become quite conspicuous in the field. This redoubled 
growth is due apparently to the fact that the underground tunnels of 
the ants loosen up the soil and have somewhat the effect of deep plow- 
ing. It is not likely that the increased growth under these condi- 
tions offsets entirely the loss in the area where no plants are allowed 
to grow, but it is sufficient to reduce the importance of the insect to 
sonic extent. Mi - . J. I). Mitchell, who has made many careful obser- 
vations on this species, believes that the actual damage inflicted is 
generally overestimated. 

The sting of the agricultural ant is at least as severe as that of a 
bumblebee. It is speedily inflicted on any animal that approaches 
the nest. Consequently, colonies located in the vicinity of houses 
or on roads or paths frequently become decided nuisances. The best 
local applications for stings are aqua ammonia or bicarbonate of 
soda (baking soda). When fainting or dizziness occurs, as i- fre- 
quently the case, a few drops of ammonia taken internally will lie 
helpful. 

NATURAL ENEMIES. 

Natural enemies exert some repressive influence upon agricultural 
ants. The most important enemy among the birds is the great - 
tailed grackle ( Megaquiscalus major ?narrourus), commonly known as 
the jackdaw. The following additional Texas birds are known to 
prey upon species of Pogonomyrmex. according to records in the 
Biological Survey: Upland plover (Bartramia Ivngicauda) , burrow- 
ing owl {Speotyto cunieularia hypogcea), Texas night hawk (Clior- 
deiles acutipennu texensis), scissor-tailed flycatcher (Museivora for- 
ficata), kingbird (Tyrarmus tyrannus), redbird (Cardinalis eardi- 
nalis), and mockingbird {Mim/us polyglottos) . The horned lizard 
(Phrynosoma comutum) includes agricultural ants as a pari of it- 



regular diet. 



REPRESS K IX. 



As in the case of the cutting ant. the destruction of this species 
can best be brought about by the use of the solution of potassium 
cyanid in water. Mr. J. D. Mitchell conducted experiments at Vic- 
toria. Tex., which showed that this was a perfectly satisfactory 
method. It is much cheaper and easier of application than in the 
case of the cutting ant on account of the fact that the underground 
portion of the nest is much less extensive. A pint of liquid is suf- 
ficient for even a large colony, though sometime- a second applica- 
tion may be necessary. 

Carbon bisulphid is also a good remedy and can be applied in 
a very simple maimer. All that i^ necessary is to pour about 2 



PWO DESTRUCTIVE ANTS, 7 

ounces into the opening of the nest. The opening need nol !><• i l 
A> tlif gas is much heavier than air, it sinks into the innermost 
i'-. ami kill- all of the ants in the colony. Setting fire to the 
liquid is of ii" benefit. In Fact, it i- likely to lessen its efficiency. The 
poison nia\ lie applied at any linn- of the day, rcgardlef of the 

number of the ant- that an tside tin' nest. The destruction 

of tin- colony depends upon tin' killing of tin' queen, and -In- remains 
in tin- not at all times, except when the swarming flight i- under 
way, tor a very short time in the spring. 

Sometimes Paris green or other arsenicals are used in the attempt 
to control this species. They air generally applied bj -imply pour- 
ing a handful into thr openings. Many of the am- an' killed, l>nt 
a large pari <>t' the brood is not affected, ami the colony -"on becomes 
a- numerous ;i- ever. In some cases where tlii- method has been 
followed persistently tin' ants have moved their nest a few fret away 
ami have become reestablished perfectly in a Bhort time For these 
reasons the use of arsenicals can not be considered satisfactory. 

Another method sometimes followed, which is of little practical 
use, i- trapping the ants in bottles, [fa large bottle is buried in the 
ground in the vicinity of tin' nest with the neck tln-h with the sur- 
face the ants soon begin an exploration ami fall inside. The noise 
they make in tin- bottle attracts many others, in tlii- way in the 
vicinity of ;i populous colony a large bottle may be filled in a short 
time. The objection to this procedure is that ii only reduces the 
strength <>t' the colony. The immature stages ami the queen are not 
affected, and the colony booh regains it- former numbers. 

Approved : 

d \mi> W'n SON, 

§ n tary of Agrit idture. 
Washington, D. C, January 18, 1912. 



ADDITION \ I. COP! 

ii in. iv I"' | nx-'ir- • 1 from the Sitkkin 
■HI ■ >»■' DOCDM ' 

Oilier, Washington, D I - <-opy 




UNIVERSITY OF FLORIDA 

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